The FindAlias Methodallows a Clientto obtain the list of Nodesthat match the provided AliasNamesearch string. The signature of this Methodis specified below, the arguments are defined in Table 3.
Signature
FindAlias(
[in] String AliasNameSearchPattern,
[in] NodeId ReferenceTypeFilter,
[out] AliasNameDataType[] AliasNodeList
);
Table 3– FindAlias Method Arguments
|
Argument |
Description |
|
AliasNameSearchPattern |
A string that can contain wild cards, use to find a list of AliasNames(see OPC 10000-4- “Wildcard Characters” table for supported wildcards) |
|
ReferenceTypeFilter |
A NodeIdthat represent a ReferenceType (i.e. AliasFor or one of its subtypes) that restricts the search. Any ReferenceTypeincludes all subtypes of that ReferenceType. |
|
AliasNodeList |
The returned list of AliasNameDataType. If no Nodesmatch the search string or have the appropriate ReferenceType, the list shall be empty. |
Methodresult codes are defined in Table 4
Table 4– FindAlias Method Error Codes
|
Result Code |
Description |
|
Bad_InvalidArgument |
The input string is not a valid search string |
|
Bad_UserAccessDenied |
The current user does not have the rights required. |
|
Bad_ResponseToLarge |
The response was to large to be returned, try new filter and repeat find |
The Methodis formally defined in Table 5.
Table 5– FindAlias Method AddressSpace definition
|
Attribute |
Value |
||||
|
BrowseName |
FindAlias |
||||
|
References |
Node Class |
BrowseName |
DataType |
TypeDefinition |
ModellingRule |
|
HasProperty |
Variable |
InputArguments |
Argument[] |
PropertyType |
Mandatory |
|
HasProperty |
Variable |
OutputArguments |
Argument[] |
PropertyType |
Mandatory |
It is important to note that there might be more than one entry for every AliasName. Multiple Serversmight provide an equivalent object (such as a temperature sensor). This Methodwill return the AliasNamesin order of preference. That is the Serverwill return what it recommends as the best match first followed by the next best match etc. The criteria for ordering are Serverspecific. The criteria might be based on the ServerStatusof the Serverthat contains the referenced Node, it might be load balancing of Servers,or it might be some other algorithm.
Clientsshould use the first usable entry in the list.